C语言实现哈夫曼编码

本文实例为大家分享了C语言实现哈夫曼编码的具体代码，供大家参考，具体内容如下

代码来自于《小甲鱼C++快速入门》

主程序main.cpp

#include "stdafx.h"
#include <stdlib.h>
#include "huffman.h"
int main()
{
 htTree *codeTree = buildTree("I love wwwwwwwwwFishC.com!");//建立哈夫曼树
 hlTable *codeTable = buildTable(codeTree);//建立编码表
 encode(codeTable,"I love FishC.com!");//对输入的字符串进行编码
 decode(codeTree,"0011111000111");//解码
 system("pause");
 return 0;
}

两个头文件:
huffman.h:定义了哈夫曼树和编码表的结构

#pragma once
#ifndef _HUFFMAN_H
#define _HUFFMAN_H
typedef struct _htNode{
 char symbol;
 struct _htNode *left,*right;
}htNode;

typedef struct _htTree{
 htNode *root;
}htTree;

typedef struct _hlNode{
 char symbol;
 char *code;
 struct _hlNode *next;
}hlNode;

typedef struct _hlTable{
 hlNode *first;
 hlNode *last;
}hlTable;

htTree *buildTree(char *str);
hlTable *buildTable(htTree *huffmanTree);
void encode(hlTable *table, char *stringToEncode);
void decode(htTree *tree, char *stringToDecode);
#endif

queue.h：定义了有序队列的结构，将字符按优先级排列，即频率从小到大排列，val是树节点，直接由队列建立起哈夫曼树

#pragma once
#ifndef _PQUEUE_H
#define _PQUEUE_H
#include "huffman.h"
#define MAX_SZ 256
#define TYPE htNode *

typedef struct _pQueueNode{
 TYPE val;
 unsigned int priority;
 struct _pQueueNode *next;
}pQueueNode;

typedef struct _pQueue{
 unsigned int size;
 pQueueNode *first;
}pQueue;

void initPQueue(pQueue **queue);
void addPQueue(pQueue **queue, TYPE val, unsigned int priority);
TYPE getQueue(pQueue **queue);
#endif

两个cpp文件实现两个头文件声明的函数：
huffman.cpp

#include "stdafx.h"
#include "queue.h"
#include "huffman.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
htTree *buildTree(char *str)
{
 int *probability = (int *)malloc(sizeof(int) * 256);
 //初始化
 for (int i = 0; i < 256; i++)
 {
 probability[i] = 0;
 }
 //统计待编码的字符串各个字符出现的次数
 for (int j = 0; str[j] != '\0'; j++)
 {
 probability[str[j]]++;
 }

 //定义队列的头指针
 pQueue *huffmanQueue;
 initPQueue(&huffmanQueue);
 //填充队列
 for (int k = 0; k < 256; k++)
 {
 if (probability[k] != 0)
 {
  htNode *aux = (htNode *)malloc(sizeof(htNode));
  aux->left = NULL;
  aux->right = NULL;
  aux->symbol = (char)k;
  addPQueue(&huffmanQueue, aux, probability[k]);
 }
 }
 free(probability);
 //生成哈夫曼树
 while (huffmanQueue->size != 1)
 {
 unsigned int newPriority = huffmanQueue->first->priority + huffmanQueue->first->next->priority;
 htNode *aux = (htNode *)malloc(sizeof(htNode));
 aux->left = getQueue(&huffmanQueue);
 aux->right = getQueue(&huffmanQueue);
 addPQueue(&huffmanQueue, aux, newPriority);
 }
 htTree *tree = (htTree *)malloc(sizeof(htTree));
 tree->root = getQueue(&huffmanQueue);
 return tree;
}

void traverseTree(htNode *treeNode,hlTable **table,int k,char code[256])
{
 if (treeNode->left == NULL&&treeNode->right == NULL)
 {
 code[k] = '\0';
 hlNode *aux = (hlNode *)malloc(sizeof(hlNode));
 aux->code = (char *)malloc(sizeof(char)*(strlen(code) + 1));
   strcpy(aux->code,code);
 aux->symbol = treeNode->symbol;
 aux->next = NULL;
 if ((*table)->first == NULL)
 {
  (*table)->first = aux;
  (*table)->last = aux;
 }
 else
 {
  (*table)->last->next = aux;
  (*table)->last = aux;
 }
 }
 if (treeNode->left != NULL)
 {
 code[k] = '0';
 traverseTree(treeNode->left,table,k+1,code);
 }
 if (treeNode->right != NULL)
 {
 code[k] = '1';
 traverseTree(treeNode->right, table, k + 1, code);
 }
}

hlTable *buildTable(htTree *huffmanTree)
{
 hlTable *table = (hlTable *)malloc(sizeof(hlTable));
 table->first = NULL;
 table->last = NULL;

 char code[256];
 int k = 0;

 traverseTree(huffmanTree->root,&table,k,code);
 return table;
}
void encode(hlTable *table, char *stringToEncode)
{
 hlNode *traversal;
 printf("Encoding......\n\nInput string:\n%s\n\nEncoded string :\n",stringToEncode);
 for (int i = 0; stringToEncode[i] != '\0'; i++)
 {
 traversal = table->first;
 while (traversal->symbol != stringToEncode[i])
  traversal = traversal->next;
 printf("%s", traversal->code);
 }
 printf("\n");
}
void decode(htTree *tree,char *stringToDecode)
{
 htNode *traversal = tree->root;

 printf("\n\nDecoding......\n\nInput string: \n%s\n\nDecoded string: \n",stringToDecode);
 for (int i = 0; stringToDecode[i] != '\0'; i++)
 {
 if (traversal->left == NULL&&traversal->right == NULL)
 {
  printf("%c", traversal->symbol);
  traversal = tree->root;
 }
 if (stringToDecode[i] == '0')
  traversal = traversal->left;
 else if (stringToDecode[i] == '1')
  traversal = traversal->right;
 else
 {
  printf("The input string is not coded correctly!\n");
  return;
 }
 }
 printf("\n\n");
 return;
}

queue.cpp：

#include "stdafx.h"
#include <stdio.h>
#include <stdlib.h>
#include "queue.h"
void initPQueue(pQueue **queue)
{
 *queue = (pQueue *)malloc(sizeof(pQueue));
 (*queue)->first = NULL;
 (*queue)->size = 0;
 return;
}
void addPQueue(pQueue **queue, TYPE val, unsigned int priority)
{
 if ((*queue)->size == MAX_SZ)
 {
 printf("\n Queue is full. \n");
 return;
 }
 pQueueNode *aux = (pQueueNode *)malloc(sizeof(pQueueNode));
 aux->priority = priority;
 aux->val = val;
 if ((*queue)->size == 0||(*queue)->first==NULL)
 {
 aux->next = NULL;
 (*queue)->first = aux;
 (*queue)->size = 1;
 return;
 }
 else
 {
 if (priority <= (*queue)->first->priority)
 {
  aux->next = (*queue)->first;
  (*queue)->first = aux;
  (*queue)->size++;
  return;
 }
 else
 {
  pQueueNode *iterator = (*queue)->first;
  while (iterator->next!=NULL)
  {
  if (priority <= iterator->next->priority)
  {
   aux->next = iterator->next;
   iterator->next = aux;
   (*queue)->size++;
   return;
  }
  iterator = iterator->next;
  }
  if (iterator->next == NULL)
  {
  aux->next = NULL;
  iterator->next = aux;
  (*queue)->size++;
  return;
  }
 }
 }
}
TYPE getQueue(pQueue **queue)
{
 TYPE returnValue;
 if ((*queue)->size > 0)
 {
 returnValue = (*queue)->first->val;
 (*queue)->first = (*queue)->first->next;
 (*queue)->size--;
 }
 else
 {
 returnValue = NULL;
 printf("\n Queue is empty \n");
 }

 return returnValue;
}

运行结果：

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